Electromagnetic devices are used for various purposes, such as a wide variety of motors and electromagnetic valves. Such an electromagnetic device may be provided partially with a nonmagnetic portion (nonmagnetic body) for the purpose of forming a desired magnetic circuit, shielding a leakage magnetic flux, and the like. In general, the nonmagnetic portion can be formed by interposing a different member that is not ferromagnetic between magnetic members or portions, and/or providing an air gap therebetween. Descriptions relevant to this are found in Patent Literature 1, for example.
According to the above approach, however, it cannot be achieved at the same time to reduce the size of an electromagnetic device, enhance the performance, and reduce cost, etc. Therefore, Patent Literature 2, for example, proposes modifying a part of a magnetic member (magnetic body) that constitutes an electromagnetic device so that the part becomes nonmagnetic. Specifically, Patent Literature 2 proposes irradiating laser to a part of a stator core that comprises martensite-based stainless steel, thereby to heat and cool the part so that the part is austenitized (becomes nonmagnetic).